Hermetically sealed machines, such as those found in micro combined heat and power (microCHP) units, often experience outgassing of unwanted hydrocarbons, other chemical species, and/or moisture, from components within the unit into the interior of the unit or machine casing at the high temperatures of operation. This can cause carburisation (carbon deposit and build up on) and/or oxidisation (corrosion) of the internal components, such as metal heat exchangers, of the machine. This can lead to power loss in the machine or complete failure of the machine.
It is an object of the present invention to provide an improved engine or at least to provide the public with a useful choice.